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Calcium and Chloride as Cofactors and Their Binding in Photosystem II
Başlık:
Calcium and Chloride as Cofactors and Their Binding in Photosystem II
Yazar:
Beravolu, Shilpa, author.
ISBN:
9780438086623
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (63 pages)
Genel Not:
Source: Masters Abstracts International, Volume: 57-06M(E).
Advisors: Alice Haddy Committee members: Chiu Norman; Jason Reddick.
Özet:
Photosystem II (PSII) is the membrane-bound protein complex which participates in the photosynthetic conversion of sunlight energy into chemical energy and produces molecular oxygen. Calcium and chloride are important cofactors that PSII requires in the process of oxygen evolution. They may be thought of as involved in a bisubstrate mechanism, where each is required for the activation of evolution of oxygen. The binding site of calcium has been identified as part of the catalytic Mn4Ca cluster, and two chloride binding sites have been identified near the catalytic cluster.
In this research, the dependence of oxygen evolution activity by PSII as a function of chloride and calcium concentrations was measured and analyzed according to enzyme kinetics methods to determine a series of KM values for Cl- activation. The data were next analyzed in terms of bisubstrate enzyme kinetics models, leading to kinetic constants for both Ca2+ and Cl- activation. While the order of binding could not be determined from the data, the results are consistent with a random sequential binding model for the two ions. Further experiments were performed to reveal details about the calcium and chloride binding sites. The possibility of using isothermal titration calorimetry (ITC) to analyze Cl- binding to PSII was explored.
Finally, the response of the Tyr Z radical, which is involved in electron transfer from the Mn4Ca cluster, was analyzed using electron paramagnetic resonance (EPR) spectroscopy, to determine the effects of the presence of Ca2+ and Cl-. The results of these studies help to clarify the relationship between the critically required activators calcium and chloride during oxygen evolution by PSII.
Notlar:
School code: 0154
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(688292.1) | 688292-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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